This invention relates to microwave electromagnetic (EM) energy generation and especially to a generator which produces high-power, EM energy from an electron beam in which the electrons are moving at relativistic speeds.
In the last few years, considerable interest has been shown in producing high-power rf radiation. This interest has arisen in part from recent developments in high-voltage technology and, particularly, the ability to produce relativistic electron beams with powers of 10.sup.9 to 10.sup.12 watts.
It is useful to classify microwave generators using electron beams into two categories. The first is generators using the "maser mechanism". Here, the amplification of the rf radiation is due to stimulated emission from an inverted population level. The second group of generators relies on an "aerial mechanism" (i.e., bunching). Here spatial and velocity nonuniformity in the electron distribution is needed.
Recent theoretical work indicates that nonlinear effects may play an important role in limiting the efficiency of a microwave maser to a few percent of the power available in a relativistic electron beam. The present device, which relies on the "aerial mechanism", converts on the order of 20 percent of the electron kinetic energy in a relativistic electron beam into rf microwave radiation.